Background: A simple quantification technique by liquid chromatography–electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) is required for regorafenib in biological matrices with bioavailability studies in healthy rabbits, when compared with reported techniques. Objective: The main aim of the research work is to develop a validated LC-ESI-MS/MS technique for the quantification of regorafenib and application to bioavailability studies in healthy rabbits. Methods: Chromatographic separation was achieved with hypersil-C18 analytical column (50mm×4.6 mm, 4µm) and a mobile phase composition of acetonitrile and 5mM ammonium acetate in the proportion of 70:30. The mobile phase was infused into the column with high pressure to get 0.7 ml/min flow rate. The total retention time of the analyte is promising when compared with the existed methods for regorafenib. Quantitation was processed by monitoring transitions of m/z -483.0/262.0 and 450.0/260.0 for regorafenib and internal standard respectively in multiple reaction monitoring. Results: The linearity equation and correlation coefficient (R2) findings were y =0.9948x+2.6624 and 0.998 respectively. The intra and inter-day precision of the developed technique was found between 1.00 – 8.50% for the QC-samples (2, 4, 240 and 480ng/ml). From bioavailability study, the drug was shown Tmax of 3.688 ± 0.754; average AUC0͢α and AUC0͢t was 6476.81 ± 259.59 and 6213.845 ± 257.892 and Cmax was found to be 676.91 ± 22.045 in healthy rabbits. Conclusion: The developed technique was validated and successfully applied in the pharmacokinetic study of drug (40 mg tablet) administered through oral route in healthy rabbits.

The selected propranolol microsphere formulation, S6 was employed for gel formulation with a variety of polymers like Carbopol 934, HPMC and Sodium CMC by mechanical stirring method in order to develop a sustained release propranolol microspheres containing bioadhesive gel. The prepared bioadhesive gels were evaluated for pH, viscosity, %drug content, in vitro drug release studies, bioadhesion, ex vivo permeation studies, accelerated stability and in vivo bioavailability studies. From all the above studies FG3 was found to be optimized formulation. In vitro experiments indicated a sustained release of 98.92% over 12 h and an acceptable bioadhesion quality for formulation FG3. Optimized formulation was characterized for FTIR, SEM and stability studies and found to be stable. Propranolol Optimized formulation exhibited significant increased bioavailability in vivo when compared with marketed tablet. The drug release from the optimized formulation follows zero order kinetics with anomalous Non-fickian diffusion. In vivo studies revealed that Propranolol Optimized formulation FG3 exhibited significant increased bioavailability when compared with marketed product, due to reduced first pass metabolism, when it is administered by the buccal route. Hence, it can be concluded that the formulation FG3 has potential to deliver Propranolol in a controlled and constant manner for prolong period over other formulations and can be adopted for a successful delivery of propranolol for buccal use.

Nimodipine, a poorly soluble drug, was considered to be fit for solid dispersions to improve its solubility and bioavailability. Our study intended to prepare Nimodipine solid dispersions by solvent evaporation method using various novel polymers. Solubility and dissolution studies indicate that Kolliwax RH 40 and SLS is the most suitable polymer. The solubility studies were corresponded with dissolution data and the formulation SD15 was found to be having highest drug release of about 98.96±5.15% in about 90 minutes. In-vitro release data from several formulations containing XRD and SEM studies indicate no crystallinity in the optimized formulation SD15.FTIR studies suggested good drug excipient compatibility between all components of prepared formulation. From in vivo bioavailability studies, Cmax of the optimized formulation SD15 was 4.34±0.08ng /ml, was significantly higher as compared to pure drug suspension, i.e., 2.78±0.35ng/ml. Tmax of optimized formulation was decreased significantly when compared with pure drug (1.00±0.05hr, 2.00±0.01hr), AUC0-α and AUC0-t for optimized solid dispersion formulation was significantly higher (p<0.05) as compared to pure drug suspension. The present study demonstrated that formulation of Nimodipine solid dispersion by solvent evaporation technique is a highly effective strategy for enhancing the bioavailability of poorly water soluble Nimodipine.

In the present study, immediate release solid dispersion of Repaglinide was formulated by solvent evaporation technique. Repaglinide solid dispersions were prepared using PEG 8000, Pluronic F 127 and Gelucire 44/14 by solvent evaporation method. A 3-factor, 3-level central composite design employed to study the effect of each independent variable on dependent variables. FTIR studies revealed that no drug excipient interaction takes place. From powder X-ray diffraction (p-XRD) and by scanning electron microscopy (SEM) studies it was evident that polymorphic form of Repaglinide has been converted into an amorphous form from crystalline within the solid dispersion formulation. The correlation coefficient showed that the release profile followed Higuchi model anomalous behavior and hence release mechanism was indicative of diffusion. From in vivo studies, the AUC0→24 h and peak plasma concentration (Cmax) was doubled when compared with pure drug. In addition, in vitro dissolution efficiency was well correlated with in vivo pharmacokinetic parameters. The obtained results suggested that developed solid dispersion might be an efficacious approach for enhancing the solubility and bioavailability of Repaglinide.

The objective of this study was to develop solid dispersions of Nifedipine which has low aqueous solubility and bioavailability. Preliminary solubility studies were carried out using various hydrophilic polymers. The formulations were then optimized and evaluated by in-vitro dissolution studies, X-ray diffraction, FTIR and SEM. Formulation with 1:4:2 ratios of Nifedipine, Labrosol and SLS was found to be the best as it possessed better drug release properties compared to pure drug and other physical mixtures. The optimized formulation SD12 was found to have better drug release of 98.74±5.19% in 90 minutes. From FTIR studies no interaction was takes place between drug and polymers. XRD peaks indicate the successful transformation of drug from crystalline to amorphous form. The final results indicate that the solid dispersion of Nifedipine remained stable over 90 days.